// MIT License

// Copyright (c) 2019 Erin Catto

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#include "test.h"

/// This tests stacking. It also shows how to use b2World::Query
/// and b2TestOverlap.

/// This callback is called by b2World::QueryAABB. We find all the fixtures
/// that overlap an AABB. Of those, we use b2TestOverlap to determine which fixtures
/// overlap a circle. Up to 4 overlapped fixtures will be highlighted with a yellow border.
class PolygonShapesCallback : public b2QueryCallback
{
public:
  
  enum
  {
    e_maxCount = 4
  };

  PolygonShapesCallback()
  {
    m_count = 0;
  }

  /// Called for each fixture found in the query AABB.
  /// @return false to terminate the query.
  bool ReportFixture(b2Fixture* fixture) override
  {
    if (m_count == e_maxCount)
    {
      return false;
    }

    b2Body* body = fixture->GetBody();
    b2Shape* shape = fixture->GetShape();

    bool overlap = b2TestOverlap(shape, &m_circle, body->GetTransform(), m_transform);

    if (overlap)
    {
      b2Color color(0.95f, 0.95f, 0.6f);
      b2Vec2 center = body->GetWorldCenter();
      g_debugDraw->DrawPoint(center, 5.0f, color);
      ++m_count;
    }

    return true;
  }

  b2CircleShape m_circle;
  b2Transform m_transform;
  b2Draw* g_debugDraw;
  int32 m_count;
};

class PolygonShapes : public Test
{
public:

  enum
  {
    e_maxBodies = 256
  };

  PolygonShapes()
  {
    // Ground body
    {
      b2BodyDef bd;
      b2Body* ground = m_world->CreateBody(&bd);

      b2EdgeShape shape;
      shape.SetTwoSided(b2Vec2(-40.0f, 0.0f), b2Vec2(40.0f, 0.0f));
      ground->CreateFixture(&shape, 0.0f);
    }

    {
      b2Vec2 vertices[3];
      vertices[0].Set(-0.5f, 0.0f);
      vertices[1].Set(0.5f, 0.0f);
      vertices[2].Set(0.0f, 1.5f);
      m_polygons[0].Set(vertices, 3);
    }
    
    {
      b2Vec2 vertices[3];
      vertices[0].Set(-0.1f, 0.0f);
      vertices[1].Set(0.1f, 0.0f);
      vertices[2].Set(0.0f, 1.5f);
      m_polygons[1].Set(vertices, 3);
    }

    {
      float w = 1.0f;
      float b = w / (2.0f + b2Sqrt(2.0f));
      float s = b2Sqrt(2.0f) * b;

      b2Vec2 vertices[8];
      vertices[0].Set(0.5f * s, 0.0f);
      vertices[1].Set(0.5f * w, b);
      vertices[2].Set(0.5f * w, b + s);
      vertices[3].Set(0.5f * s, w);
      vertices[4].Set(-0.5f * s, w);
      vertices[5].Set(-0.5f * w, b + s);
      vertices[6].Set(-0.5f * w, b);
      vertices[7].Set(-0.5f * s, 0.0f);

      m_polygons[2].Set(vertices, 8);
    }

    {
      m_polygons[3].SetAsBox(0.5f, 0.5f);
    }

    {
      m_circle.m_radius = 0.5f;
    }

    m_bodyIndex = 0;
    memset(m_bodies, 0, sizeof(m_bodies));
  }

  void Create(int32 index)
  {
    if (m_bodies[m_bodyIndex] != NULL)
    {
      m_world->DestroyBody(m_bodies[m_bodyIndex]);
      m_bodies[m_bodyIndex] = NULL;
    }

    b2BodyDef bd;
    bd.type = b2_dynamicBody;

    float x = RandomFloat(-2.0f, 2.0f);
    bd.position.Set(x, 10.0f);
    bd.angle = RandomFloat(-b2_pi, b2_pi);

    if (index == 4)
    {
      bd.angularDamping = 0.02f;
    }

    m_bodies[m_bodyIndex] = m_world->CreateBody(&bd);

    if (index < 4)
    {
      b2FixtureDef fd;
      fd.shape = m_polygons + index;
      fd.density = 1.0f;
      fd.friction = 0.3f;
      m_bodies[m_bodyIndex]->CreateFixture(&fd);
    }
    else
    {
      b2FixtureDef fd;
      fd.shape = &m_circle;
      fd.density = 1.0f;
      fd.friction = 0.3f;

      m_bodies[m_bodyIndex]->CreateFixture(&fd);
    }

    m_bodyIndex = (m_bodyIndex + 1) % e_maxBodies;
  }

  void DestroyBody()
  {
    for (int32 i = 0; i < e_maxBodies; ++i)
    {
      if (m_bodies[i] != NULL)
      {
        m_world->DestroyBody(m_bodies[i]);
        m_bodies[i] = NULL;
        return;
      }
    }
  }

  void Keyboard(int key) override
  {
    switch (key)
    {
    case GLFW_KEY_1:
    case GLFW_KEY_2:
    case GLFW_KEY_3:
    case GLFW_KEY_4:
    case GLFW_KEY_5:
      Create(key - GLFW_KEY_1);
      break;

    case GLFW_KEY_A:
      for (int32 i = 0; i < e_maxBodies; i += 2)
      {
        if (m_bodies[i])
        {
          bool enabled = m_bodies[i]->IsEnabled();
          m_bodies[i]->SetEnabled(!enabled);
        }
      }
      break;

    case GLFW_KEY_D:
      DestroyBody();
      break;
    }
  }

  void Step(Settings& settings) override
  {
    Test::Step(settings);

    PolygonShapesCallback callback;
    callback.m_circle.m_radius = 2.0f;
    callback.m_circle.m_p.Set(0.0f, 1.1f);
    callback.m_transform.SetIdentity();
    callback.g_debugDraw = &g_debugDraw;

    b2AABB aabb;
    callback.m_circle.ComputeAABB(&aabb, callback.m_transform);

    m_world->QueryAABB(&callback, aabb);

    b2Color color(0.4f, 0.7f, 0.8f);
    g_debugDraw.DrawCircle(callback.m_circle.m_p, callback.m_circle.m_radius, color);

    g_debugDraw.DrawString(5, m_textLine, "Press 1-5 to drop stuff, maximum of %d overlaps detected", PolygonShapesCallback::e_maxCount);
    m_textLine += m_textIncrement;
    g_debugDraw.DrawString(5, m_textLine, "Press 'a' to enable/disable some bodies");
    m_textLine += m_textIncrement;
    g_debugDraw.DrawString(5, m_textLine, "Press 'd' to destroy a body");
    m_textLine += m_textIncrement;
  }

  static Test* Create()
  {
    return new PolygonShapes;
  }

  int32 m_bodyIndex;
  b2Body* m_bodies[e_maxBodies];
  b2PolygonShape m_polygons[4];
  b2CircleShape m_circle;
};

static int testIndex = RegisterTest("Geometry", "Polygon Shapes", PolygonShapes::Create);
